Embodiments of a first aspect of the present invention relate to the subterranean creation of lost circulation material (LCM) from the rock debris inventory within a bored passageway, used to inhibit fracture initiation or propagation within the walls of the passageway through subterranean strata. Apparatuses for employing this first aspect, may be engaged to drill strings to generate LCM in close proximity to newly exposed fracturable strata walls of the bored portion of the passageway through subterranean strata, for timely application of said subterranean generated LCM to said walls.
Embodiments of rock breaking tools incorporating this first aspect can include: passageway enlargement tools (63 of FIGS. 5 to 7), eccentric milling tools (56 of FIGS. 8 to 9), bushing milling tools (57 of FIGS. 10 to 12) and rock slurrification tools (65 of FIGS. 15 to 39). Usable embodiments of passageway enlargement tools and eccentric milling tools are dependent upon embodiments of managed pressure conduit assemblies (49 of FIGS. 145 to 166) selected for use. The embodiments of said bushing milling tools represent significant improvements to similar conventional tools described in U.S. Pat. No. 3,982,594, the entirety of which is incorporated herein by reference. Embodiments relating to rock slurrification tools (65 of FIGS. 15 to 39) represent significant improvements to conventional above ground technology, described in U.S. Pat. No. 4,090,673, the entirety of which is incorporated herein by reference, placed within a drill string to generate LCM from rock debris in a subterranean environment. The embodiments relating to said rock slurrification tools break rock debris or other breakable materials placed in a slurry through impact with a rotating impellor, or through centrifugally accelerating said rock debris or added material to impact a relatively stationary or opposite rotational surface.
Embodiments of the rock breaking tools further use rock slurrification and milling of a rock debris inventory generated from a drill bit or bore hole opener to generate LCM, while conventional methods rely on surface addition of LCM with an inherent time lag between detection of subterranean fractures through loss of circulated fluid slurry and subsequent addition of LCM. Embodiments of the present invention inhibit the initiation or propagation of strata fractures by generating LCM from a rock debris inventory urged through a bored passageway by circulated slurry coating the strata wall of said passageway, before initiation or significant propagation of fractures occur.
Due to its relatively inelastic nature, rock has a high propensity to fracture during boring and pressurized slurry circulation. With the timely application of LCM, embodiments of the present invention may be used to target deeper subterranean formations prior to lining a strata passageway with protective casing, by improving the differential pressure barrier, known as filter cake, between subterranean strata and circulated slurry, by urging lost circulation material into pore spaces, fractures or small cracks in said wall coated with circulated slurry in a timely manner to reduce the propensity of fracture initiation and propagation. Packing LCM within the filter cake, covering the pore spaces of whole rock, inhibits the initiation of fractures by improving the differential pressure bearing nature of said filter cake. Various methods for limiting initiation and propagation of fractures within strata exist and are described in U.S. Pat. No. 5,207,282, the entirety of which is incorporated herein by reference.
Embodiments of the present invention, including rock breaking tools (56, 57, 63, 65), slurry passageway tools (58 of FIGS. 42 to 70, 88 to 118 and 121 to 124) and managed pressure conduit assemblies (49 of FIGS. 145 to 166), use mechanical and pressurized application of subterranean generated LCM to supplement and/or replace surface added LCM to strata pore and fracture spaces, further re-enforcing said filter cake's differential pressure bearing capability to further inhibit the initiation or propagation of fractures with the timely application and packing of said LCM, referred to by experts in the art as well bore stress cage strengthening. Conventional methods, generally, require that boring be stopped to perform stress cage strengthening of the well bores, while embodiments of the present invention may be used to continuously vary pressure exerted on the well bore, strengthening the well bore during boring, circulation and/or rotation of a conduit string carrying said embodiments.
Embodiments of a second aspect of the present invention relate to the ability to emulate casing drilling and liner drilling placement of a protective lining within subterranean strata without requiring removal of the drill string. Additionally this second aspect may be used to place sand screens, perforating guns, production packers and other completion equipment within the subterranean strata. Once a desired subterranean strata bore depth is achieved, embodiments of the slurry passageway tool (58 of FIGS. 42 to 70, 88 to 118 and 121 to 124) or managed pressure conduit assembly (49 of FIGS. 145 to 166) detach one or more outer concentric strings and engage said strings to the passageway through subterranean strata. This second aspect of the present invention can be combined with embodiments of rock breaking tools (56, 57, 63, 65) employing the first aspect of the present invention to reduce the propensity of fracture initiation and propagation until the second aspect of the present invention isolates subterranean strata with a protective lining. This undertaking removes the risks of first extracting a drilling string and subsequently urging a liner, casing, completion or other protective lining string axially downward within the passageway through subterranean strata, during which time the ability to address subterranean hazards is limited.
Embodiments of a third aspect of the present invention relate to the ability to urge cement slurry axially downward or axially upward through a first annular passageway between the subterranean strata and a protective lining, engaging said lining with the walls of a passageway through subterranean strata using embodiments of the slurry passageway tool (58 of FIGS. 42 to 70, 88 to 118 and 121 to 124).
Conventional methods of cementation rely on pushing cement slurry axially upward through a first annular passageway, while the third aspect of the present invention may use the higher specific gravity of said cement slurry to aid its urging axially downward through said first annular passageway, effectively permitting the slurry to fall into place with minimum applied pressure. As cementation at the upward end of said protective lining is the most crucial for creating a differential pressure barrier isolating weaker shallow strata formations, gravity assisted placement of the third aspect of the present invention significantly increases the likelihood of placing cement slurry at the upward end without incurring losses to the strata compared to conventional methods.
Embodiments of said slurry passageway tool may also be provided with a flexible membrane (76 of FIGS. 58 to 59, and 88 to 93) functioning as a drill-in casing or liner shoe, preventing axially upward or downwardly placed cement from u-tubing once placed, without removing the internal drill string or forcing cement through sensitive apparatus such as motors and logging tools or drilling equipment in said internal drill string.
After cementation occurs and said inflatable membrane prevents u-tubing, the internal drill string of a dual conduit string application (49 of FIGS. 145 to 166), may be used to continue boring a subterranean passageway while the placed cement is hardening.
While cementation is the prevalent application for the third aspect of the present invention, any fluid slurry, including drilling or completion fluids, may be diverted axially downward or upward through the first annular passageway with embodiments of the slurry passageway tool (58 of FIGS. 42 to 70, 88 to 118 and 121 to 124). In instances of high annular frictional factors, circulation of drilling or completion fluids, including placing gravel packs or drilling ahead with losses, the friction of a limited clearance of a first annular passageway may be used to slow the loss of slurry while maintaining a hydrostatic head and/or gravity assisted flow when circulating any fluid.
Embodiments of a fourth aspect of the present invention remove the need to select between the annular slurry velocities and associated annular pressure regimes of conventional methods of drilling, liner drilling and casing drilling. Using this fourth aspect, the more significant annular velocity and associated annular pressure benefits may be emulated with a large diameter string (49 of FIGS. 145 to 166) used to carry a protective lining with the drilling assembly.
Conventional methods for performing operations within a passageway through subterranean strata require the exclusive selection of liner drilling or casing drilling high annular velocities and associated annular pressures if a protective lining is to be used as a drill string. Embodiments of the present invention (49 of FIGS. 145 to 166) carry a protective lining with a drill string allowing the selection of a lower annular velocity and annular pressure of a traditional drill string until said lining is engaged with the strata wall, after which a drill string may continue to drill ahead having never been removed from the passageway through subterranean strata as described in the third aspect of the present invention. If a plurality of protective linings are carried with the internal drill string, a succession of protective linings may be placed without removing the internal drill string as described in the liner drilling embodiment of FIG. 159.
Liner drilling is similar to casing drilling with the distinction of having a cross over apparatus to a drilling string at its upper end. As said cross over apparatus is generally not disposed within the subterranean strata and has little effect on annular velocities and pressures experienced by the strata bore, liner drilling and casing drilling are referred to synonymously throughout the remainder of the description.
Additionally, where the large diameter of prior casing drilling apparatus provide the benefit of a slurry smear effect, generally inapplicable to smaller diameter drilling strings, embodiments of the managed pressure conduit assembly (49 of FIGS. 145 to 166) also emulate said smear effect without requiring higher annular velocities and frictional losses associated with conventional casing drilling by directing an internal annular passageway flow in the same axial direction as circulated fluid in the annular passageway between strata and the drill string, thus increasing flow capacity and decreasing velocity and associated pressure loss in the direction of annular flow.
Embodiments incorporating the fourth aspect of the present invention may emulate smear effects, annular velocity and associated pressures of drilling or casing drilling. Contrary to conventional methods of casing drilling, embodiments of the managed pressure conduit assembly (49 of FIGS. 145 to 166) have a plurality of internal circulating passageways that may be directed in a plurality of directions by a slurry passageway tool (58 of FIGS. 42 to 70, 88 to 118 and 121 to 124) to emulate the annular velocity and frictional losses of either conventional drilling or conventional casing drilling apparatus in the first annular passageway between a tool string and the passageway through subterranean strata.
Embodiments of a fifth aspect of the present invention relate to the ability repeatedly select and reselect fluid slurry circulation velocity and associated pressure emulations in a plurality of directions, through use of the third and fourth aspects of the present invention, described above, with embodiments of a multi-function tool (FIGS. 73 to 87, and 125 to 131) used to control the connection of passageway by embodiments of a slurry passageway tool (58 of FIGS. 42 to 70, 88 to 118 and 121 to 124).
Embodiments of a sixth aspect of the present invention relate to the ability to incorporate various selected embodiments of the present invention into a single tool (49 of FIGS. 145 to 166) having a plurality of conduit strings with slurry passageway tools (58 of FIGS. 42 to 70, 88 to 118 and 121 to 124), multi-function tools (FIGS. 73 to 87, and 125 to 131) controlling said slurry passageway tools, and subterranean LCM generation tools (56, 57, 63, 65 of FIGS. 5 to 39) to realize benefits of the first five aspects and target subterranean depths deeper than those currently possible using conventional technology.
A need exists for systems and methods for increasing available amounts of LCM for timely application to subterranean strata to subsequently reduce the propensity of strata fracture initiation or propagation.
A need exits for systems and methods for engaging protective liners, casings and completion equipment with subterranean strata without the need to remove a drill string.
A need exists for systems and methods to gravity assist the circulation slurry and cement slurry axially downward or axially upward between liners, casings, completions, other protective linings and the subterranean strata without affecting slurry sensitive internal drilling and completion equipment, such as mud motors, logging while drilling equipment, perforating guns and sand screens.
A need exits for drilling-in sensitive completion components, after which the drill string may be used as a production or injection string.
A need exists for methods and systems emulating the annular velocities and associated pressures of prior art drilling or completion strings in sensitive strata formations susceptible to fracture without losing smear effects, carriage of a protective linings or adversely affecting sensitive equipment within said strings.
A further need exists for systems and methods where the selection of said annular velocities, associated pressures and smear effects are not exclusive, but repeatable during the repeated urging of a passage through subterranean strata and engaging a protective lining to said passageway, without the need to remove the internal drill string exposing well operations to the risks of exiting and re-entering said passageway.
Significant hazards and costs exist for the exclusive selection of benefits associated with existing technology that when multiplied by the number of passageways and protective linings placed, represents a significant cost of operations.
A need also exists for systems and methods generally applicable across subterranean strata, susceptible to fracture, to reach deeper depths than is currently the practice or realistically achievable with existing technology prior to placement of protective drilling and completion linings.
The present invention meets these needs.